Route reliability record
SEA→AUS
Seattle to Austin
- Flights
- 2,090
- Period
- September 2025 to August 2026
- Distance
- 1,770 mi
- Carriers
- 3
This route lands a B+, about a point better than the national rate of 77.3%. About one flight in five arrives 15 minutes late or worse, and those flights are late by about an hour on average. That rests on 2,090 SEA to AUS flights, of which Delta Air Lines flew 950 at 80.1% on time.
Best time to fly SEA to AUS: a 5am–8am departure, ideally on a Tuesday. Flights in that window arrived on time 89.1% of the time and Tuesday flights 84.4%, against 78.5% for the route overall.
The US average over the same twelve months is 77.3%, so there is little to separate this route from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
78.5%
Arrivals under 15 minutes late, of 2,071 completed flights
Avg delay
55 min
Across delayed arrivals only, not all flights
Cancelled
0.81%
National rate is 1.89%
Best carrier
Delta
80.1% on time across 950 flights
These figures cover 2,090 flights between September 2025 and August 2026. The median arrival is 4 minutes early, which is the part an average hides: most flights here are fine, and the on-time rate is decided by a tail of badly late ones. On-time means under 15 minutes late, the DOT's own threshold.
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Carrier by carrier
Which airline is most reliable on SEA to AUS
The two carriers here are closely matched: half a point separate the best from the worst. At that spread, schedule and price are better tie-breakers than reliability. Sample sizes are shown so you can see which rows are worth weighing.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Delta Air Lines | 950 | 80.1% | 67 min | 1.05% | B |
| Alaska Airlines | 1,051 | 80.1% | 44 min | 0.67% | B+ |
| Southwest Airlinesthin sample | 89 | 42.7% | 57 min | 0.00% | F+ |
No carrier stands out. Delta tops the table at 80.1%, half a point clear of the bottom, which is inside the range this kind of sample moves year to year.
Flight by flight
Flights on SEA to AUS
The flight numbers below flew this route at least 250 times in the period, busiest first. Each has its own record, with its schedule and delay causes.
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Best ways to make this trip
The most reliable ways to fly Seattle to Austin
Every airline on this route, ranked by how often a scheduled flight actually operated and arrived on time, with its best departure time and most punctual flight number. No nearby airport pair beat these.
| Option | Airline | Success | On time | Cancelled | Best departure | Most punctual flight |
|---|---|---|---|---|---|---|
| 1. SEA → AUSSeattle to Austin | Alaska Airlines | 79.6% | 80.1% | 0.67% | 8pm–5am, Tue | AS 352 11:47 |
| 2. SEA → AUSSeattle to Austin | Delta Air Lines | 79.3% | 80.1% | 1.05% | 5am–8am, Tue | DL 739 07:15 |
Success is the share of scheduled flights that operated and arrived less than 15 minutes late, so a cancelled flight counts against it. “(route)” means the best time comes from every carrier on the route rather than this airline alone.
Departure window
The best time of day to leave
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 66 points, against half a point between the best and worst carrier.
- 5am–8am278 flights89.1%
- 8am–11am486 flights81.8%
- 11am–2pm644 flights77.0%
- 2pm–5pm39 flights23.1%
- 5pm–8pm613 flights75.9%
- 8pm–5am30 flights83.3%
Scale runs 15% to 95%.
Book the early departure. Flights leaving between 5am–8am arrive on time 89.1% of the time, against 23.1% for the afternoon window. That is 66 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 11am–2pm window is the busiest, with 644 flights scheduled in it.
Explore
Filter SEA to AUS by airline, time, month and day
Pick a breakdown and a carrier. The dashed mark on each row is the same slice for every US flight.
On SEA to AUS, the best departure window is 5am–8am at 89.1% on time and the worst is 2pm–5pm at 23.1%, a wide gap of 66.0 points. All US flights leaving 5am–8am ran 89.3%.
- 5–8am89.1%
- 8–11am81.8%
- 11am–2pm77.0%
- 2–5pm23.1%
- 5–8pm75.9%
- 8pm–5am83.3%
best all US flightsScale 15% to 95%.
Across the year
When delays peak on this route
This route's year swings by 26 points from best month to worst, which is wide. An annual average tells you very little about the week you are actually flying, so read the strip rather than the headline if your dates are fixed.
July is the worst month at 62.7% on time, 26 points below April, the best at 88.2%. Summer afternoon convection and peak-season schedules land on the same weeks every year, so this is a pattern you can book around rather than a run of bad luck. July was the busiest month here, with 217 flights.
Across the week, Tuesday is the strongest day at 84.4% on time and Monday the weakest at 72.6%, a spread of 12 points.
Delay causes
Why this route gets delayed
Carrier accounts for 43% of the 25,000 delay minutes carriers reported here, and the remaining four split what is left.
- 43%Carrier
- 30%Late-arriving aircraft
- 24%National Airspace System
- 3%Extreme weather
The largest share of delay minutes, 43%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 11,000 of the 25,000 delay minutes reported here. The split is drawn from 24,590 reported delay minutes.
The practical consequence: the 5am–8am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 89.1% on time here.
Cancellations are rare at 0.81%, below the national 1.89% and low enough to earn the plus on the grade. Roughly one flight in 100 is called off; the risk here is arriving late, not not arriving.
Connections and stage length
What a delay here actually costs
5.4% of arrivals land an hour or more late, close to the national 8.3%, so a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last about an hour, which a normal layover absorbs.
At 1,770 miles this is transcontinental flying, and long routes get a quiet structural advantage. Scheduled block time on a flight this length carries more padding in absolute minutes, so a twenty-minute late departure often still becomes an on-time arrival. Read the on-time rate here as slightly flattering next to a short-haul route with the same operational quality.
The return leg runs 81.3% on time across 2,089 flights, within 3 points of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.
The sample behind these figures is 2,090 flights, enough that the headline rate is stable to within roughly a point. The hour-block and month splits divide that further, so read the thinner bars with more caution than the headline.
Work out the risk of missing a connection in AUS after this flight
What to do with this
Booking this route
Put together: the calendar is the biggest lever here, not the carrier or the hour. April runs 88.2% on time and July 62.7%, a swing of 26 points. If the dates move at all, move them out of July before you think about anything else. 2,071 completed flights over 12 months sit behind that.
Common questions
SEA to AUS questions
How often is SEA to AUS delayed?
About one flight in five arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 21.5% of the 2,090 flights in this analysis, against 22.7% nationally. Delayed flights are late by about an hour on average.
Which airline is most reliable on SEA to AUS?
Delta Air Lines leads at 80.1% on time across 950 flights. Alaska Airlines is at the other end on 80.1%, a gap of half a point. Sample size matters as much as the percentage: a rate built from a few hundred flights moves around far more than one built from ten thousand.
What time of day has the fewest delays on SEA to AUS?
The 5am–8am departure window is the strongest at 89.1% on time. The 2pm–5pm window is the weakest at 23.1%, 66 points behind. Later departures inherit delays from earlier flights the same aircraft has already flown, which is why the curve slopes the way it does.
How bad are July delays on SEA to AUS?
July is the weakest month at 62.7% on time, compared with 88.2% in April. Across the year that is 26 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.
Related
Where to go next
- AUS to SEA — the return legseparate record
- Seattle-Tacoma International (SEA) delay statistics
- Austin-Bergstrom International (AUS) delay statistics
- Delta Air Lines on SEA to AUS80.1%
- Alaska Airlines on SEA to AUS80.1%
- SEA to LAX, a related route82.0%
- DEN to AUS, a related route76.2%
- SEA to PHX, a related route78.2%
- Delta Air Lines on-time record80.1%
- Alaska Airlines on-time record80.1%
- Southwest Airlines on-time record42.7%
- The best time of day to fly, according to 7.05 million flight records
- Worst months to fly in the US, ranked by the data
Direction matters. SEA to AUS and AUS to SEA are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.
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Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.